Parallel abutments and circumferentially extended pads

ABSTRACT

In a vehicle disc brake comprising a caliper structure adapted to straddle the brake disc, each of the two parts of the caliper, which lie on opposite sides of the disc being formed with surfaces extending perpendicular to the plane of the disc for guiding one of a pair of opposed brake pads, the pad-guiding surface at each of the circumferentially spaced ends of each pad is divided into two separate coplanar portions with a gap between them and the pad is so shaped and dimensioned that at each end it projects circumferentially outwards beyond the plane of the respective guiding surface, through the gap between the two portions thereof.

United States Patent [22] Filed [45] Patented June 12, 1969 Oct. 12,1971 [73] Assignee Girling Limited [32] Priority June 26, 1968 [33]Great Britain [31] 30,555/68 [54] PARALLEL ABUTMENTS ANDCIRCUMFERENTIALLY EXTENDED PADS 2 Claims, 4 Drawing Figs.

[56] References Cited UNITED STATES PATENTS 3,261,429 7/1966 Burnett etal.... 188/733 X 3,375,906 4/1968 Hayes 188/733 3,442,356 5/1969 Hahm188/724 Primary Examiner-George E. A. l-ialvosa A!t0rney Scrivener,Parker, Scrivener and Clark ABSTRACT: In a vehicle disc brake comprisinga caliper structure adapted to straddle the brake disc, each of the twoparts of the caliper, which lie on opposite sides of the disc beingformed with surfaces extending perpendicular to the plane of the discfor guiding one of a pair of opposed brake pads, the pad-guiding surfaceat each of the circumferentially spaced ends of each pad is divided intotwo separate coplanar portions with a gap between them and the pad is soshaped and dimensioned that at each end it projects circumferentiallyoutwards beyond the plane of the respective guiding surface, through thegap between the two portions thereof.

PAT E NTED IIBI 1 2 am sum 2 or 2 PARALLEL ABUTMENTS ANDCIRCUMFERENTIALLY EXTENDED PADS This invention relates to vehicle discbrakes of the kind comprising a caliper structure formed in two partssecured together, the jointing surfaces of the two parts lying in aplane parallel to that of the disc, the two parts together providing apair of caliper halves disposed respectively on opposite sides of thedisc and a bridge portion which straddles the disc and joins the twohalves together, each caliper half being formed with surfaces extendingperpendicular to the plane of the disc for guiding one of a pair ofopposed brake pads.

in accordance with the invention the pad-guiding surface at each end ofeach pad comprises two separate coplanar portions, spaced apart radiallyof the disc, and the pad projects circumferentially outwards beyond theplane of the guiding surface between the two separate portions thereof.This arrangement allows the area (and hence the volume) of pad materialto be increased for a given spacing of the guiding surfaces.

The invention is particularly but not exclusively applicable to vehicledisc brakes constructed in accordance with the teaching of the copendingapplication for Pat. Ser. No. 808,066 filed Mar. 18, 1969 and is furtherdescribed below in its application to such a brake.

One particular form of brake in accordance with the invention will nowbe described in detail, by way of example, with reference to theaccompanying drawings, in which:

FIG. 1 is a view in elevation of the brake with the disc removed;

FIG. 2 is a plan view;

FIG. 3 is a view in elevation as in FIG. 1 with part of the caliperremoved; and

FIG. 4 is a sectional side view along the line AA in FlG. 3.

The brake caliper or housing is made up of two castings land 12 boltedtogether by connecting bolts 14 which pass through the bridge section ofthe caliper straddling the outer edge of the disc 16; the caliper havinga split line 18 coinciding with the center plane of the disc and definedby matching faces 20 and 22 on the respective parts 10 and 20.

The two halves of the caliper which lie on opposite sides of the discand are connected together by the bridge section are each formed with apair of spaced hydraulic cylinders 24 and 26 containing sealed andbooted working pistons 28 and 30 for moving a friction pad assembly 32into engagement with the disc. The pad assembly which is spigotted tothe pistons for radial retention, is positioned between a pair ofparallel plane abutment surfaces 34 which serve to guide the pad foraxial movement, perpendicular to the plane of the disc, and also asabutments preventing circumferential movement of the pad and absorbingthe drag force during braking.

The guiding and abutment surface 34 at each of the circumferentiallyspaced ends of the pad comprises two separate coplanar portions 34A and34B spaced apart radially of the disc with a gap between them, the pad32 projecting circumferentially outwards through this gap beyond theplane of the surfaces 34. The pad 32 comprises a block of frictionmaterial 31 having one face secured to a metal backing plate 33, theopposite face of the block 31 being exposed for engagement with the faceof the brake disc 16. The end faces of the portions 36 and 37 of thebacking plate engage respectively the surfaces 34A and 34B andintermediate these terminal portions the end face of the pad projectsbeyond the common plane in which they lie.

The caliper bridge section consists of a central portion 38 and flankportions 40 and 42 which between them define a pair of windows 44 and 46for pad inspection purposes, and their size and spacing is such that thepad-guiding surfaces 34 are also exposed to view.

One-half of the caliper is provided at its radially inner end with apair of mounting lugs 48 and 50 which are positioned in line with therespective windows 44, 46. In each caliper half, the alignment of theguiding surfaces 34 with the respective windows 44, 46 enables thesesurfaces and the jointing surface or 22 to be machined in a sin lepasswith a rectilinear stroke of a cutting tool, e.g. by roachmg ormilling. Furthermore, in the case of caliper half 10, the inner surfaces52 of the lugs 48 and 50 can be machined in the same pass.

The hydraulic cylinders are arranged in two opposed pairs (the actuationof either pair being sufiicient to move the pads into engagement withthe brake disc) and the two pairs are connected into two separate andindependently operated groups of opposed pot actuators, The cylinders ofeach pair, lying on opposite sides of the caliper, are interconnected byinternal drilling passing across the bridge section.

1 claim:

1. A disc brake for a vehicle comprising a disc adapted to be connectedto the wheel of a vehicle for rotation therewith, a caliper comprisingtwo halves disposed respectively on opposite sides of the disc andhaving a mutual joint plane parallel to the plane of the disc, meanscarried by one of the halves for rigidly connecting the caliper to avehicle, said halves including abutting parts straddling the disc anddefining a caliperbridging portion, bolts passing through said bridgingportion and securing said caliper halves together, a pair of inwardlyfacing, circumferentially spaced, guiding and torque sustaining surfacesin each caliper half perpendicular to the plane of the disc, eachsurface being in two separate coplanar portions adjacent the outer andinner sides of each respective caliper half, said portions being spacedapart from each other radially of the disc and defining between them anopen space, a paid in each caliper half having circumferentially spacedends, each end having substantially radially spaced inner and outerparts, complementary with and slidably engaging the correspondingspaced-apart coplanar guiding surfaces in said caliper halves, each endof each of said pads being constructed and arranged to projectcircumferentially outwardly beyond the plane of each respective guidingsurface and into the open space between the two separate portionsthereof and means in each caliper half for urging the brake pad thereintowards the adjacent surface of said disc.

2. A vehicle disc brake as defined in claim 1 wherein said bridgingportion includes two pad inspection windows spaced apartcircumferentially of the disc, and each having circumferentially spacedinner and outer sides, said bolts pass through said bridging portionbetween the windows and on each side of them, both portions of each ofsaid pad guiding surfaces being aligned with a respectivecircumferential outer side of one of said windows.

1. A disc brake for a vehicle comprising a disc adapted to be connectedto the wheel of a vehicle for rotation therewith, a caliper comprisingtwo halves disposed respectively on opposite sides of the disc andhaving a mutual joint plane parallel to the plane of the disc, meanscarried by one of the halves for rigidly connecting the caliper to avehicle, said halves including abutting parts straddling the disc anddefining a caliper bridging portion, bolts passing through said bridgingportion and securing said caliper halves together, a pair of inwardlyfacing, circumferentially spaced, guiding and torque sustaining surfacesin each caliper half perpendicular to the plane of the disc, eachsurface being in two separate coplanar portions adjacent the outer andinner sides of each respective caliper half, said portions being spacedapart from each other radially of the disc and defining between them anopen space, a paid in each caliper half having circumferentially spacedends, each end having substantially radially spaced inner and outerparts, complementary with and slidably engaging the correspondingspaced-apart coplanar guiding surfaces in said caliper halves, each endof each of said pads being constructed and arranged to projectcircumferentially outwardly beyond the plane of each respective guidingsurface and into the open space between the two separate portionsthereof and means in each caliper half for urging the brake pad thereintowards the adjacent surface of said disc.
 2. A vehicle disc brake asdefined in claim 1 wherein said bridging portion includes two padinspection windows spaced apart circumferentially of the disc, and eachhaving circumferentially spaced inner and outer sides, said bolts passthrough said bridging portion between the windows and on each side ofthem, both portions of each of said pad guiding surfaces being alignedwith a respective circumferential outer side of one of said windows.